1. Field of the Invention
The present invention relates to movable devices and in particular to game devices such as balls, and to concepts for detecting any contact of an object with the movable device.
2. Description of Prior Art
For quite some time, various interest groups have wished to study and understand the sequence of movements of moving objects and/or persons, which requires an exact indication of the object's position in space and time. What is of particular interest here are, among other things, game balls, in particular in commercialized types of sport, such as footballs, or soccer balls, which are highly accelerated in three-dimensional space, as well as tennis or golf balls. The question of who was the last to touch the object of the game, how it was hit and in which direction it was accelerated further may be decisive for the outcome of the game, depending on the type of game.
Game devices that are used in high-performance sports, such as tennis balls, golf balls, footballs and the like, nowadays can be accelerated to extremely high speeds, so that the detection of the object during the movement requires highly sophisticated technology. The technical means employed so far—mainly cameras—either completely fail to meet the requirements set forth above, or meet them only to an insufficient degree; also the methods, hitherto known, for position finding by means of various transmitter and receiver combinations still leave a large error margin with regard to the spatial resolution of the position indication, with regard to the ease of use of the transmitter/receiver components required, and above all with regard to evaluating the data obtained by means of the transmitter/receiver system, so that it is not yet possible, or at least requires a large amount of effort, to evaluate the results obtained from this data as fast as possible.
It is not only in the field of commercial sports, where movable game devices may be employed, but it is also in the personal field that users have become more and more used to electronic devices indicating various pieces of information to give a user feedback as to how he/she has affected an object, or to provide him/her with information about how a player has affected a gaming device.
Current statistics methods in commercial applications, such as of the German first football division (Bundesliga), work with recording relatively simple statistics, such as the percentage of ball contacts of a team or the number of corners, free kicks or fouls.
On the other hand, there have been means, for example in tennis, where there is a very plannable, clearly arranged environment with only two players, which measure, for example, the speed of the tennis ball at the serve, such that a viewer is in a position to assess whether a serve was “hard” or “soft”.
What is problematic about such speed measurements which may occur by optical methods is the fact that they do not function within an environment where there is a muddle of players, such as on a football pitch where there are not only two persons being active, but 22 persons, who, in addition—unlike in tennis for a serve—are not positioned in more or less the same place but may form any constellation on the pitch. On the other hand, particularly in football, it is interesting, both for the feedback of the players in training and for the viewers to know, for example, how a shot actually came about and/or how large the force of the shot was.
Thus, kicking a ball in football or soccer or hitting a ball in tennis represents the actual “base” impact, as it were, on the game device which is always decisive of how the game continues, since ultimately everything is about doing something with the movable game device, such as playing it into an opponent's field (as in tennis) or moving it into a goal (as in football, or soccer) or into a basket (as in basketball) or to cause it to contact the floor of the opponent's pitch (as in volleyball). Due to the difficulty of the continuously changing constellations in dynamic games, in particular team games, however also in tennis when no serve is currently played, but the ball is played in one move, external speed measurements will fail, which has lead to the fact that there are currently no shot force detection systems that could be employed in a flexible manner.
On the other hand, for the field of sports, but also for the field of leisure, there is a further limitation resulting from the fact that these fields are highly commercialized. All systems providing additional information, in particular when they are intended for leisure of for leisure sports, must enable to be offered at a low price since they are objects which a user never “absolutely needs” but might like to have anyway. Particularly in such a market, it is decisive to be able to offer a robust system at low price. For example, a system must not require a high level of maintenance or of equipment such as, for example, a speed measurement system for measuring the serve of a tennis player. Due to the relatively high cost associated, a small tennis club would never acquire such a system for training purposes, which applies even more to a private person who wishes to play tennis in a slightly more ambitioned manner in his/her leisure time.
It is the object of the present invention to provide a concept for measuring a shot force exerted on a movable game device, the concept being applicable in a flexible manner while being low in expense.
In accordance with a first aspect, the invention provides a device for measuring a shot force exerted on a movable game device, including:
a provider for providing a time curve, which occurs when the game device is impacted by an object, of an acceleration acting upon the object, or a time curve of a pressure of the game device;
a processor for processing the time curve of the acceleration or the time curve of the pressure to obtain an energy measure which depends on an energy transferred onto the object by the shot;
a provider for providing information about the shot force on the basis of the energy measure.
In accordance with a second aspect, the invention provides a movable game device including:
an acceleration sensor for providing a time curve of an acceleration, or a pressure sensor for providing a time curve of a pressure of the game device which occurs while an object impacts the game device; and
an outputter for outputting the time curve of the acceleration or pressure.
In accordance with a third aspect, the invention provides a method for measuring a shot force exerted on a movable game device, the method including the steps of:
providing a time curve, which occurs when the game device is impacted by an object, of an acceleration acting upon the object, or a time curve of a pressure of the game device;
processing the time curve of the acceleration or the time curve of the pressure to obtain an energy measure which depends on an energy transferred onto the object by the shot;
providing information about the shot force on the basis of the energy measure.
In accordance with a fourth aspect, the invention provides a computer program having a program code for performing the method for measuring a shot force exerted on a movable game device, the method including the steps of:                providing a time curve, which occurs when the game device is impacted by an object, of an acceleration acting upon the object, or a time curve of a pressure of the game device;        processing the time curve of the acceleration or the time curve of the pressure to obtain an energy measure which depends on an energy transferred onto the object by the shot;        providing information about the shot force on the basis of the energy measure,when the program runs on a computer.        
The present invention is based on the findings that a shot-force measurement which is accurate, low in maintenance and, at the same time, may be used in a flexible manner may be achieved in that a time curve of an acceleration or a time curve of an internal pressure of a movable game device is provided so as then to process this time curve, specifically with the aim of obtaining a measure of energy which depends on the energy transmitted to the object by the shot. In addition, a means for providing information about the force of the shot is provided which uses the synergy measure for determining the force of the shot. Thus, in accordance with the invention, what is performed is not direct speed measurement but, in preferred embodiments, at the most an indirect speed measurement, to the effect that a temporal acceleration curve and a temporal pressure curve are detected, and that is these time curves, or temporal curves, are processed to obtain a measure of energy, that is some quantity which is somehow connected to the energy in a linear or non-linear or in some other manner. This measure is then used in accordance with the invention to provide force-of-shot information. This force-of-shot information may be a quantitative value which is, however, free from units, e.g. on a scale between 1 and 10, or it may be a value on an open-ended scale, or it may be a value representing a force exerted on the movable game device at the time of the shot, or it may be an energy value, i.e. a value of the energy imparted on the movable game device at the shot.
Alternatively, the shot force may also be an indication of length providing a measure of how far the ball would have flown, for example, if the ball had been shot at an optimum angle and without any rotation. Such a shot-force result is interesting, in particular, for ball sports such as soccer or American football, since to the players there, a measure of length, for example how far a pass or kickout will have gone, means more than quantitative values or physical force or energy units. However, for a comparison with other players, the non-unit quantitative scale is highly interesting, whether it is finite or open-ended.
In preferred embodiments, ball contacts are also detected. Here, various components may be employed for both tasks. To this end, the use of two signals having different signal speeds is ideal to achieve a robust but nevertheless efficient and accurate detection of a contact with a movable device. Thus, in accordance with the invention, a detector within the movable device, e.g. in a football, detects whether an object, such as a player's leg, is located in the vicinity of the football. This is effected, for example, by pressure, acceleration or vibration measurement or by non-contact measurement.
Once a detection has been made to the effect that the object is located in the vicinity of the movable device, the transmitter module is controlled to transmit two signals having different signal speeds. A receiver device connected to the object will detect the first signal and then wait for a certain time period for reception of the second signal having a lower signal speed. If the signal having the lower signal speed is detected within the predetermined time period which starts upon reception of the first, fast signal, it shall be assumed that the object which has received both the first and, within the predetermined time period, also the second signal, was in contact with the movable device. This is reflected in that a detector which has detected reception of the second signal within the predetermined time period provides a detector output signal, a memory subsequently storing the fact that there has been a detector output signal, i.e. that it is very likely for a ball contact to have occurred. Alternatively or in addition, an absolute moment in time at which the detector signal has occurred may be stored in the memory, so that when one thinks of a football match, a sequence of moments result which may then, e.g. after a match or during a match, be read out to ascertain, as a function thereof, how many ball contacts a player had, or generally speaking, how many contacts an object had with the movable device.
If one assumes that, e.g., several football players are near a ball, the fast signal will be detected by several receiver devices. However, if the predetermined time duration is selected such that it is very likely that really only that receiver device which is located closest to the movable device can receive the second signal within the predetermined time period, while receiver devices which are more remote will also receive the second signal, but only after the predetermined time duration has expired, no ball contact will be registered for those players.
By setting the predetermined time duration in the receiver devices worn, or carried, by the player, it is thus possible to set the accuracy and/or the range to be detected. For this purpose, no access to the ball itself is required.
In addition, the use of two signals of different speeds allows to dispense with any complicated and, thus, failure-prone electronics in the ball itself. One only needs to make sure that the ball has a proximity detector which operates in a contact-controlled or non-contact manner and which will then control the transmission of the two signals of different delay times. Thus, no complicated electronics are required within the ball itself, which is a considerable advantage in particular since the forces and accelerations acting on the ball may be huge, so that there is a very rough environment for there to be an electronic system within the ball.
On the receiver side, no personal identification or the like is required, which is of considerable advantage—particularly if one considers that what is dealt with here is a mass product, i.e. that may players are to be provided with receiver devices—since thus, all receiver devices may operate in an identical manner and do not require any specific identification, which also renders the receiver devices simple and low in or even completely free from maintenance. In addition, a simple and robust structure also ensures safety from tampering.